Vehicles are generally equipped with air-conditioning systems for cooling/heating the interior thereof. Such an air-conditioning system includes a compressor, as one of the components of a cooling system, which compresses a low-temperature and low-pressure gas refrigerant introduced from an evaporator to convert it into a high-temperature and high-pressure gas refrigerant, and which transfers the converted gas refrigerant to a condenser.
As an example of a compressor serving to compress a refrigerant in a vehicle cooling system, there are a reciprocating compressor which compresses a refrigerant during reciprocation and a rotary compressor which compresses a refrigerant during rotation. The reciprocating compressor includes a crank compressor which transfers a driving force from a drive source to a plurality of pistons using a crank, a swash plate compressor which transfers a driving force from a drive source to a rotary shaft equipped with a swash plate, and a wobble plate compressor which utilizes a wobble plate. The rotary compressor includes a vane rotary compressor which utilizes a rotary shaft and a vane, and a scroll compressor which utilizes an orbiting scroll and a fixed scroll.
Referring to FIGS. 1 to 3, a scroll compressor 100 includes a housing 200, a fixed scroll 300 provided inside the housing 200, a drive motor 400 which drives an orbiting scroll 600, an eccentric bush 500 which is coupled to a rotary shaft 410 of the drive motor 400, and the orbiting scroll 600 which is coupled to the eccentric bush 500 to revolve around the fixed scroll 300 and defines a compression chamber.
The orbiting scroll 600 is eccentrically coupled to an eccentric shaft 411 of the rotary shaft 410 by the eccentric bush 500. The eccentric bush 500 serves to turn the orbiting scroll 600 using rotary power transferred from the rotary shaft 410. The eccentric bush 500 is integrally formed with a balance weight 550 for balancing it according to the eccentric rotation thereof.
As illustrated in FIG. 3, when the rotary shaft 410 rotates together with the eccentric bush 500, a tip surface 412 of the rotary shaft 410 comes into frictional contact with a bushing surface 510 of the eccentric bush 500. In this case, since the bushing surface 510, i.e. the sliding surface, has a poor surface roughness, sludge is generated due to friction when a compressor is driven, resulting in contamination in a compression space.
That is, the whole shape of the eccentric bush 500 is formed by forging, and a portion of the eccentric bush 500, which requires accurate dimensions, is additionally processed by a lathe. In a cutting process by the lathe, the center portion of the lathe, as a center of rotation, has a low cutting speed, and therefore the surface of the eccentric bush 500 is rough. Accordingly, when the processing of the eccentric bush 500 is completed in the state in which it has a rough sliding surface, the surface of the sliding surface is cut during friction with the rotary shaft 410 of the drive motor 400.